Some specifications, such as the 3rd Generation Partnership Project (3GPP), Technical Specification (TS) Group Radio Access Network, Evolved Universal Terrestrial Radio Access (E-UTRA), Requirements for support of radio resource management (Release 12), 2013-12 (hereinafter 3GPP TS 36.133) and 3GPP TS Group Radio Access Network, Requirements for support of radio resource management (FDD), (Release 12), 2013-12 (hereinafter 3GPP TS 25.133), may define how many different carriers for intra-frequency, inter-frequency, and inter-radio access technology (RAT) neighbor cell searches and level measurements a given user equipment may need to be able to monitor.
Connected mode discontinuous receive (DRX) refers to a user equipment monitoring a physical downlink control channel (PDCCH) in a discontinuous manner according to rules and parameters defined in for example 3GPP, TS Group Radio Access Network, E-UTRA, Medium Access Control (MAC) protocol specification, (Release 12, hereinafter TS 36.321). When the user equipment in DRX is not required to monitor the PDCCH, the user equipment in DRX may turn off (for example, make inactive) its receiver hardware to reduce receiver power consumption.